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<?xml version="1.0" standalone="yes"?> <Paper uid="C96-2126"> <Title>MULTITALE: linking medical concepts by means of frames</Title> <Section position="4" start_page="0" end_page="746" type="metho"> <SectionTitle> CC Pathology (indicating pathological concepts), CC Interventional Equipment (indicating the instrument), CC Combi (a term which has a medical meaning only ira </SectionTitle> <Paragraph position="0"> combination with another-medical- term), r T. 1,'rizzanin (syntax), A. Kramer (lexicon), 1. Maks (syntax and semantics), W. Martin (overall supervision) CC modifier_bodyside,CC_modifierextent, CC_modifier_number (terms which modit~C/ other medical terms.</Paragraph> <Paragraph position="1"> The Surgical deed concept is classified into 12 subtypes, among others: CS_remove, CS close, CS_create, CS close, CS install, CS make appear. The Surgical decd concept is considered as the nncleus of the surgical procedure and may have different types of relationships with the other&quot; medical concepts: the R Direct object indicates the object on which the surgical deed is carried out; the R_Indirect_Object indicates the object to or from or in which the surgical deed is carried out; the R_Location indicates the place where the Surgical Deed is carried out; the Rmeans indicates that with which the Surgical Deed is carried out; the R nmnner indicates how the Surgical I)ecd is carried out.</Paragraph> <Paragraph position="2"> The next example illustrates the CEN\TC251-model. The input is taken fl'om a report of a ncurosurgical intervention; the output is generated by the MULTITALI,; system.</Paragraph> <Paragraph position="3"> (ex. 1) INPUT: Enkele fragmenten discus worden nog verw!/derd, dan worden met een beitelOe de osteofytaire randen van de dekplaat weggenomen.</Paragraph> <Paragraph position="4"> (Some J?agments of the discus are removed, therec~er the osteophytie edges of the cover plate are taken away mith a cell beiteltje CC_ interv eqtfip s notre de osteofytaire randen van de dekplaat R dir ob. ect CCAmthology S NP dekplaat CC_ _anatomy S houri weggenomen CC_surg deed CS_remove s ycrb t P. dirobject de osteofytaire randen win de dekphmt I P,_means met een beiteltie 2 ill. OVI<RAI,L ARCIlITECTURE</Paragraph> </Section> <Section position="5" start_page="746" end_page="746" type="metho"> <SectionTitle> MUI/ITI'ALE SYSTEM OF TIlE </SectionTitle> <Paragraph position="0"> The MUI,TITAI,E system consists of 5 modules : 1. - A syntactic tagger and lcmmatizer for l)utch medical language.</Paragraph> <Paragraph position="1"> 2. - A syntactic module lbr the lbrmation of minimal NPs and PPs. 'l'he syntactical module functions as a preprocessor. As a consequence syntax is kept to a minimum and partial: only clause segmentation, verbdetection and NI'/PI' demarcation is considered to be necessary.</Paragraph> <Paragraph position="2"> 3. - A module for the attribution of concept typc to the minimal NPs and PPs. Given syntactical &quot;chuncks&quot; (verbs, NPs, PPs) within a certain space (ehmse), MUI/1TFALE tries to assign eolmepts to them. The system is preferential in that it has defined - based upon corpus observation and sublanguage modelling - a priority ranking/hierarchy of concepts when occurring in combination, to lbrm one complex concept. This priority ranking/hierarchy looks as follows: It governs the concept type calculus so that e.g. in an expression with a Surgical Deed, the latter overrules all other concepts as in rechler \]CC-Modifier-lk}dyside\] retromasloidale ICC-Anatomyl incisie \[CC-Surgicat deed\]. So, too in tire expression oste@taire \[CCl'ath{}logy\] randen \[CC-Combi\] van de dekplaat \]CC-Anatt}my\] tile Pathology concept will overrule the other COlrccpts.</Paragraph> <Paragraph position="3"> 4.- A linking module for linking surgical deeds concepts with other medical concepts witllin the clause. 5.- A guessing module for suggesting the concept type of tmkn(}wn w(}rds '\['he last two modules will bc discussed in scction IV. and V. I}elow.</Paragraph> <Paragraph position="4"> ...... surgical deed clause limit s =: synlactic tag</Paragraph> <Paragraph position="6"> stlbtypc lag I)uring this process MUI/I'ITAI,E uses the following knowledge bases: (A) the st,rgical deed lexicon: a lexicon of surgical deed concepts, containing about 250 tokens with their COllcepl type (CC st, rgical._deed), surgical deed subtype and part-of-speech (=<CAT>).</Paragraph> <Paragraph position="7"> <lemma> wegnelllen to remove <cat> verb <concept type> CC surgical decd <concept subtype>CS remove <endlemma> (B) the non-surgical-deed-lexicon: a lexicon of nonsurgieaMeed concepts, containing about 800 tokens with their concept type and part-of-spcech <lemma> beitet chisel <cat> north <concept type> CC intervent .equipment <endlemma> (C) the type lexicon: a knowledge base with an entry for each of the 12 surgical deed subtypes and 1 &quot;neutral&quot; subtype . For each entry are specilied, the possible Senmntic Links and the possible concept types related with those Semantic IAnks. I:or an example see section V.2 (ex. 8c) and section V.3 (ex. 10).</Paragraph> <Paragraph position="8"> (D) a database with prepositions and their ftmctions</Paragraph> </Section> <Section position="6" start_page="746" end_page="746" type="metho"> <SectionTitle> TIlE IANKING MOI)ULE INTRODUCTION </SectionTitle> <Paragraph position="0"> The input of tile linking module is the sentence segmented in NPs , I'Ps and verbs wilh - if relevant - their concept type (assigned by the concept type assigmncllt module).:</Paragraph> <Paragraph position="2"> met een I,eiteltje \[Pl' CC lnterventional Equipment\] The task of the linking module is to combine the concepts of the sentence in order to build a colnpositc surgical procedure concept, respecting the CEN norms. Since the C\]:,N-model has much in common with Filhnore's Case Grammar (Filhnore, 1968), Case grammar-like fi'ames fi)r the implementation of the model have been used. Case grammar gives an analysis of a sentence, centered around lhe verb. CEN gives an a,mlysis of a surgical procedure, centered arotmd the Surgical deed concept (which is often a verb). The definition o1&quot; the cases of Case (hammar is similar to the definition of CIC/N Semantic I,inks, both of them expressing relations between w,'ious parts of the sentence. In Case grammar, selection restrictions arc specilied lbr cases, in CIiN those parts of the sentence which are candida|e lbr a Semantic lank, refer to erie of tire CliNodel\]ned medical concepts.</Paragraph> <Paragraph position="3"> 7 4 &quot;7 (ex. 3) Het aneurysma wordt afgeelipt met een rechte clip.</Paragraph> <Paragraph position="4"> (The aneurysm is cut off with a straight clip) Considering a sentence like example 3, the system has to decide which noun phrase can be related to the verb and what is the nature of that relationship. The possible Semantic Links correspond to the CEN Semantic Links.</Paragraph> <Paragraph position="5"> So, in relation to the verb afelippen (to cut off) we find among others- Direct Object and Means. Like for Case Grammar, there are markers, like prepositions or the lack of prepositions, which point to a certain Semantic Link.</Paragraph> <Paragraph position="6"> In the above example, the preposition met (with) is an indicator for Means and it is the absence of a preposition which points to the Direct Object. For identifying the Scmantic I,inks, three particular kinds of information are needed: 1. the surgical deed concept and its possible Semantic Links 2. the NP and its concept type 3. the Prepositions and their values (l values).</Paragraph> <Paragraph position="7"> Frames are chosen for the implementation of the model. They have a top level which is fixed and represents things that are true of a certain situation. They have a lower level with slots, conditions on the slots and fillers, which represent things that are expected for a certain situation (Minsky, 1975). As regards the top level, three different kinds of frames are defined for Multitale.</Paragraph> <Paragraph position="8"> a. standard surgical deed frame: The lower level of the non-surgical-deed frame will be discussed below being different from the lower level of both the surgical-deed-frames. The lower level of the surgical deed frames contains sets of slots for the identification of Semantic I,inks. The set consists of a slot -called ROLE- for the type of Semantic Link, a slot -called ARG- lbr the pointer to the clement in the sentence which is linked to the surgical deed concept, a slot -called CC tbr the concept type' of the element which is linked and finally a slot -called IND- for the indication (I-value) of the function of the linked element. Each slot can specify conditions its filler must meet.</Paragraph> <Paragraph position="9"> The conditions on the fillers are found in the surgical deed lexicon and the type lexicon. The type lexicon gives general information for the surgical deed subtype; the surgical deed lexicon gives information for the individual token, the individual surgical deed concept.</Paragraph> </Section> <Section position="7" start_page="746" end_page="749" type="metho"> <SectionTitle> IV.2 THE LINKING MODULE STEP BY STEP </SectionTitle> <Paragraph position="0"> For filling in the frame and analyzing the sentence, the system performs the following steps for each Surgicaldeed-clause. null (ex. 4a) .. de catheter wordt in de wond geplaatst (the catheter has been installed in the wound) a. consultation of the surgical deed lexicon for finding the subtype entry ofplaatsen in the surgical deed lexicon: e. if necessary, adaptation of the frame with information from the surgical deed lexicon will take place. d. if necessary, adaptation of the fl'ame will be carried out il' the surgical deed concept is a noun o,&quot; a non-finite tbr,n of the verb.</Paragraph> <Paragraph position="1"> Thc subtype frame is specified for the finite form of the verb and the past participle. If the st.rgical deed concept is a noun or an infinitive form of the verb, the R direct object is marked by thc preposition wm (I_valuc = l_van). Therefore, the condition on the <lND>-slot of thc R Direct_object, will be changed to Ivan.</Paragraph> <Paragraph position="2"> e. filling in the slots: (ex. 4b) .. de catheter wordt in de wend geplaatst There is only one set of slots, expressing the link between two non-surgi-cal-deed concepts in a sentence: (ex. 5) ..het intracellair gedeelte van de tumor wordt uitgecuretteerd.. null (the intracellar part of the turnout is cleaned) The prepositional phrase van de tumor modifies the noun phrase her intra- cellair gedeelte. The link between these two phrases is called post-modification link. The slot POS(ition) in combination with the constraint +1 requires that the postmodifying phrase directly tbllows the NP fi)r which this frame is defined.</Paragraph> <Paragraph position="3"> (ex. 6-a) non-surgical-deed frame with slots filled in: We have established an order for tim matching of the Semantic Links, giving priority to these Links which connect a surgical deed concept with another concept. (ex. 7) ..waarna de Jkontale lob wm z~jn adherenties wordt vrijgemaakt null (.. after that the frontal lobe has been freed ... ) The specifications of van zijn adherenties, CC pathology and 1 van mect both the conditions on the filler lbr tim R indirect object of the surgical deed concept and the conditions on the filler of the R POST MOD of the non-surgical-deed concept. Since the R lndirect_Object precedes the R_Post Mod van zijn adherenties will be linked - correctly - with vrijgemaakt.</Paragraph> <Paragraph position="4"> V. THE GUESSING MODULE V. 1 INTRODUCTION The guessing module of the Multitale system deals with the semi-automatic augmentation of the concept lexicons (=lexicons of surgical deeds and non- sm'gical deeds). The performance of the tagger depends Rn&quot; a great deal on the completeness of the lexicon. If the lexicon does not contain a medical term, the tagger cannot assign a semantic link to this unknown term and another one in the sentence. The guessing module is an important help tbr the attgmentation of the concept lexicon, and consequently an important part of the Multitale system when tagging unknown texts. The lunction of the module is twofold: 1. - generation of a list of words which m'e likely to be medical terms and CEN concepts. The list does not present just a list of words unknown to the system but a selection of words relevant to CEN.</Paragraph> <Paragraph position="5"> 2. - suggestions regarding the concept type tbr each word of the generated list. The suggested concept types arc CC_surgical_deed (without subtype) ,CCanatomy, CC~mthology, CC intervent equipment and CC_way. The module works semi-automatically: the list of unknown words is generated in an automatic way, but the user of the system has to decide whether the suggestion is correct or not before adding it to the lexicon.</Paragraph> </Section> <Section position="8" start_page="749" end_page="749" type="metho"> <SectionTitle> V.2 GUESSING NON-SURGICAL-DEED CONCEPTS </SectionTitle> <Paragraph position="0"> The guessing module uses the frames of the linking module. For the guessing of the non-surgical-deed concepts, it uses the constraints given tbr the fillers of the slots of the surgical deed frame. The general rule is the following: if a phrase (noun phrase or prepositional phrase) has a Semantic Link with a surgical deed concept, at least one of the words of the phrase is a CEN- concept. Suppose a sentence contains a surgical deed concept, but the system is not able to make a semantic link between the surgical deed concept and another concept in the surgical-deedclause. In most cases, this is due to the fact that the concept type of the terms is not known, for example: (ex. 8) .. de tunor wordt verwo'derd..</Paragraph> <Paragraph position="1"> -de tumor CC-? -verwijderd CC surgical_deed CS remove (.. the turnout will be removed..) Suppose that tumor is not present in the lexicon, then the system is not able to meet the conditions of the slots of verw(/deren and cannot indicate the R_directobject. The l__wflue of de tumor meets the required value for the slot <IND>, but none of the concept classes required for the The guessing module then 'relaxes' the conditions set and now considers the syntactic function of a noun phrase or a prepositional phrase (expressed by its Ivalue) as a sufficient indication for a semantic link. In other words: if the I value of an element in the surgical-deed- clause satifies one of the i+values rcquired for an <IND> slot, then the element will be linked.</Paragraph> <Paragraph position="2"> The next step is to make a guess about tbe concept type of the filled-in element. The constraints - CC pathology, CC_colnbi and CC_anatomy (see frame \]br verwijderen) of the <CC> slot, are considered as good candidates. To be able to make a choice for one of them, the constraints are connected with priority numbers, obtained by corpus observation: (ex. 8c) part of the entry CS remove of the type lexicon: <rol>..</Paragraph> <Paragraph position="3"> The numbers are based on the occurrences of combinations of concept types in the corpus. These occurrences are translated into priority numbers for the constraints on the <CC> slots which are registered in the type and surgical deed lexicon* The concept type with the highest occurrence (in combination with the given surgical deed concept and the given Semantic Link) was marked with the highest priority number (namely 1). The concept type with the highest number is considered the most likely candidate for the filled-in clement. So, the system will suggest the concept type CC pathology lbr tumor in (ex. 8). In most cases the element, for which the concept type is guessed, consists of more than one word: (ex. 9) * om de laterale tumorale expansie te kunnen verwijderen.. -de latcrale tumorale expansie CC-? R DIRECT OBJECT -verwijderen CC_surgical_deed CS remove (.. to be able to remove the tumoral expansion) The guessed concept type is suggested for all the nouns and adjectives, being the meaningful words in the phrase. Words which have a meaning in general language are marked <GEN>, to indicate that the guess is morc questionable than in other cases.</Paragraph> <Paragraph position="4"> results of the guessing module for (ex.) 9: laterale CC_pathology? tmnorale CC_pathology? expansic CC_pathology? 3&quot;he suggestion is only correct for tumorale, whereas laterale is of the type MC bodyside and expansie of the CC combi. In a later phase we intend to correct these cases of overgeneration.</Paragraph> </Section> <Section position="9" start_page="749" end_page="750" type="metho"> <SectionTitle> V.3 GUESSING SURGICAL DEED CONCEPTS </SectionTitle> <Paragraph position="0"> The general rule for the guessing of sm'gical deeds is: each verb that has a Semantic Link with a CEN-concept, is a surgical deed concept. For finding the unknown surgical deed concepts, Multitale makes use of the fi'ames as well. For each verb in the text that is not in the concept lexicon, a frame is built. This li'ame is called CS neutral, its semantic constraints - the allowed concept types - and its syntactic constraints - the I values - are less strict than the constraints which have been specified for the frames of the surgical deeds belonging to a specific snbtypc. Because of the 'neutral' character of tim fiamc, no priority information can be given, so every constraint is labelled with the same degree o1' prinrity(=l).</Paragraph> <Paragraph position="1"> If the verb has at least one of the Semantic Links of the entry CS neutral, it will be considered as a surgical deed concept: (ex. 11) .. word! de peritoneale drain intercutaan Eetunneld .. -peritoncale drain \[CC intervent equipment</Paragraph> </Section> class="xml-element"></Paper>